Nothing weird. Installed them and they shifted fine. I ride with my hands over the lever so wasn’t shifting with 1 finger as Nic suggests in that review. Perhaps that makes a difference with leverage and the shape of the R2C compared to the normal shifters. Don’t know.
Haven’t followed RTC shifters in terms of different versions or iterations so no help there.
From memory… there were sram specific and shimano specific versions of RCT. They didn’t mix and match well. Suggest ensuring the RCT index specification matches the rear mech. For 10s, I ran SRAM RCT with a Force derailleur and shimano cassettes in back and a shimano D/A front. Worked well.